Now boasting a 10.1-million-carat reserve, Dominion Diamond’s (TSX:DDC) Sable pipe could begin production in 2019 and continue to 2027, helping keep the company’s Ekati plant at full capacity until 2033. Dominion released pre-feasibility highlights on February 22 for an open pit 17 kilometres north of Ekati’s existing infrastructure in the Northwest Territories’ Lac de Gras region.

Dominion holds an 88.9% interest in Ekati’s Core zone, which includes Sable. The company has a 65.3% stake in the adjacent Buffer zone and its Jay pipe, with Archon Minerals TSXV:ACS holding the remaining 34.7%. Jay’s January 2015 pre-feas envisioned that pipe as a standalone operation. But in September Dominion decided to defer Jay production to give Sable higher priority.

Using a one-millimetre cutoff, Sable’s pre-feas shows a probable reserve of 12 million tonnes averaging 0.8 carats per tonne for 10.1 million carats.

The resource estimate used a 0.5-millimetre cutoff, with rounded numbers showing:

The study provides all dollar amounts in U.S. currency based on a 2015 exchange rate of C$1.33. With a 7% discount rate, Dominion’s share of the post-tax net present value comes to $137 million and the post-tax internal rate of return comes to 16.2%. The study assumed a base case diamond price of $140, $50 less than last September’s PEA. The lower price results from a re-evaluation of size frequency and price per size, weaker diamond prices and additional recovery of smaller stones, Dominion stated.

Total capital expenditures would reach $55 million in fiscal 2017, $72 million in 2018 and $15 million in 2019, with another $85 million for pre-stripping, which would mostly take place in 2019.

The company plans to begin building the fully permitted mine in fiscal 2017 without a full feasibility study. Production would begin in 2019. Dominion stated it “plans to re-evaluate and further optimize the Sable mining and processing schedule based on the results of the Jay feasibility study, which is currently underway.” Jay’s probable reserve contains 84.6 million carats.

The company has previously stated that Jay could potentially extend Ekati’s mining life by at least 10 years beyond 2020. Ekati’s Misery Main pipe, with a reserve of 14 million carats, has production scheduled to begin in H1.

The world’s third-largest rough producer by value, Dominion also holds the smaller portion of a 40/60 joint venture with Rio Tinto NYE:RIO in Diavik, another Lac de Gras operation. The mine’s fourth pipe, the 10-million-carat A21, has production scheduled for H2 2018.